Process for the manufacture of crotonic acid from crotonaldehyde



Patented Feb. 13, 11923.

THEODOR .ODINGA, OF BASEL, SWITZERLAND, ASSIGNOR LONZA, OF GAMPEL,CANTON 9F VALAIS,

e FFH@E.\

T ELEKTRIZITATSWERK AND BASEL, SWITZERLAND.

PROCESS FOR THE MANUFACTURE OF CROTONIC ACID FROM CROTONALDEHYDE.

N0 Drawing.

To all whom it may concern."

Be it known that I, THEODOR ODINGA, a citizen of the Swiss Republic andresident of Basel, Switzerland, havin invented a new and useful Processfor the Crotonic Acid from Crotonaldehyde, of which the following is afull, clear, and exact specification.

From the literature (Kekul, Liebigs ,10 annalen 162, pagelll, secondparagraph) it is known that crotonaldehydeis transformed in the air, byabsorption of oxygen, into crotonic acid.-

I have found, that this oxidation can be accelerated extraordinarily bycatalysis, when a manganic salt is employed as catalyst. For theoxidation of acetaldehyd to acetic acid, there are already employed,according to the German Patent salts of manganese, as manganous acetate,maganous formate, etc., which dissolve by the action of the aldehyde andof the oxygen with a brown coloration, forming thereby an activemaganese compound. The use of this methodof formation of acetic acid forthe formation of crotonic acid meets with difliculties, for the reasonthat the crotonic acid, which is ox'idizable, is attacked more or lessaccording to the temperature; thereby the active maganese catalystbecomes in time inactive and is regenerated only slowly even at a lowtemperature and erated at all. g Nevertheless I have found that thesetroubles can be avoided, if one works for instance at ordinarytemperature and employs for the oxidation a catalyst formed by amanganic salt soluble in the rbaction liquid. Under these conditions noappre- 40 ciable destruction of the crotonic acidstakes place and thecatalyst remains undiminished active. Asproof' of the activity of thecatalyst there may be mentioned that the absorption of oxygen is aboutthe tenfold of that. which takes place, under the same conditions, whenno catalyst is employed.

As catalyst can be employed every manganic salt which is soluble incrotonaldehyde alone or mixed with a convenient solvent.

is often not regen- The manganese can be added also in form of fAnplication filed June 14, 1921.

anufacture of Serial No. 477,562.

manganese salts. of lower or higher degrees of oxidation and can beoxidized or reduced in the solution itself to the active degree that isto say a manganic salt by adding convenient oxidizing or reducingagents. Oxygen alone is sufficient to convert a manganous salt into anactive manganic compound. But if a manganic salt is used one has anactive, catalyst from the beginning; manganic acetate is particularlysuitablgl with a solvent such as glacial acetic aci Example.

preparation of the active catalyst 10 gr. of manganous acetate isdissolved :in 100 com. of glacial acetic acid and to this solution thereare added, at about 115 (1., y portions, 1.5 gr. of permanganate. Thedeep-dark-brown solution of manganic salt is diluted for the employ withglacial acetic For the acid to a manganese content of 1-2 per thou-.

sand. F or example, 209 com. of such an initial solution of 2 perthousand "are energetically agitated in a retort of half a liter, whilecooling with water, and there are added progressively thereto 150 gr. ofcrotonaldehyde, while oxygen is passed through the retort. With a goodstirring the absorption of oxygen exceeds 20 liters per hour. When nofurther oxygen is absorbed, the reaction is interrupted and the glacialacetic acid is distilled off, preferably in vacuo, on a water bath. Theresidue solidifying immediately in the cold can be purified by adistillation in vacuo or by a recrystallization from water. The yield ofpure crotonic acid is 98 to 99 per cent. of the crotonaldehyde employed.

Instead of oxygen mixtures of oxygen with indifferent gases canbe'employed. The crotonic acid and its derivatives are com; poundcapable of reacting, which may be employed to the most varioussyntheses. Technically valuable is for instance the butyric acid, whichcan be prepared there from'by reduction.

WVhat I claim is The herein described process for the manuactureofcrotonic acid from crotonaldehyde, consisting oxidizing with oxygen myname this 28th day of May, 1921, in the crotonaldehyde diluted withglacial acetig presence of two subscribing witnesses.

acid at ordinary temperature with the ai of a catalyst formed by amaiiganic salt sole THEODOR ODINGA' 5 uble in a mixture ofcrotonaldehyde and of Witnesses:

glacial acetic acid. FRIDA Rtmz, I

. In witness whereof I have hereunto signed AMAND RITTER.

